1. Field of the Invention
This invention relates generally to tape cassettes, and more particularly is directed to improvements in magnetic tape cassettes of the type in which the magnetic tape may be withdrawn from the cassette housing for recording and reproducing information signals on the tape.
2. Description of the Prior Art
The conventional tape cassette is provided with a plurality of openings at the front side of the cassette housing through which a magnetic recording and/or reproducing head, a pinch roller, capstan and the like may be inserted into the cassette housing to record and/or reproduce signals on the tape while the latter is driven or transported in a predetermined direction. However, in such a tape cassette, the number and size of the openings that may be formed in the cassette housing are limited and this, in turn, limits the number and size of the magnetic heads that may be employed for recording and reproducing operations. Accordingly, in existing magnetic tape recording and reproducing apparatus intended for use with tape cassettes of the described type, that is, in which the tape remains wholly within the cassette housing during recording and reproducing operations, the same magnetic head which is used for reproducing signals recorded on the tape is also used, in association with an erasing head, for recording new signals on the tape. It is known that the use of the same magnetic head for both recording and reproducing operations limits the quality of the audio or other information signals that may be recorded and reproduced thereby. Further, when the magnetic recording and/or reproducing head is inserted into the cassette housing for engagement with the tape therein, as aforesaid, it is difficult to ensure the precise positioning of the tape relative to such head, and variations of the position or path of the tape relative to the recording and/or reproducing head also deleteriously affects the quality of the recorded and reproduced signals.
Therefore, when it is desired to obtain high quality recording and reproducing of audio or other information signals, it has been the usual practice to employ apparatus of the open-reel type having separate or individual heads for respectively recording and reproducing signals on the tape which is precisely guided relative to such heads in the run of the tape between the supply and take-up reels. However, apparatus of the open-reel type has the well known disadvantages of requiring the manual threading of the leader or end portion of the tape from the supply reel past the guide pins and heads, and between each capstan and associated pinch roller to the take-up reel when installing a tape on the apparatus, and of requiring rewinding of the entire tape onto the supply reel when one tape is to be exchanged for another.
In order to avoid the above described disadvantages of recording and reproducing apparatus of the open-reel type and the limitations on the quality of recording and reproduction previously attainable with cassette-type recording and reproducing apparatus, it has been proposed, for example, as disclosed in United Kingdom Patent Specification No. 1,121,125, published July 24, 1968, to provide a cassette from which the tape is withdrawn when signals are to be recorded or reproduced thereon by means of respective magnetic heads which are disposed outside of the cassette housing. In the apparatus as disclosed in the foregoing patent, tape guides mounted on swingable arms and a pinch roller are initially inserted into the cassette housing and then displaced relative to the latter for withdrawing the tape from the cassette housing and into engagement with the magnetic heads and capstan. However, in cassettes intended for use with such apparatus, the tape is exposed at the exterior of the cassette housing even when the cassette is not in use, so that the exposed tape is susceptible to being damaged or even severed and will collect dust thereon.
The exposure of the tape when the cassette is not in use may be avoided by the cassette arrangement disclosed in U.S. Pat. No. 3,900,171, issued Aug. 19, 1975, and having a common assignee herewith. In such cassette, the housing has an opening extending along one of its sides and is provided with a lid which is normally spring-biased and locked to cover the tape extending across such opening of the cassette housing when the cassette is not in use and thereby protects the tape from damage thereto. However, in this previously proposed tape cassette, the lid is arranged to open in the upward direction, so that, when the cassette is disposed in its operative position, a specific lid opening means is required in addition to a tape withdrawing means. Thus, the described tape cassette is disadvantageous in that it limits the design and leads to complexity in the construction of the tape loading device, which is to be provided for withdrawing the tape from the cassette.